1. Field of the Invention
This invention relates to a high peak power microwave generator using light activated switches.
2. Description of the Prior Art
The increasing need for high power pulse microwave sources for radar and electronic counter measure applications has focussed attention on the advantages of solid state devices by reason of their size, weight and reliability. The prior art has utilized the following semiconductor devices as microwave sources: bipolar transistors, field effect transistors, Gunn effect diodes and avalanche diodes.
Typical of the prior art is U.S. Pat. No. 3,628,171 to Kurokawa et al for "Microwave Power Combining Oscillator Circuits". In accordance with the teachings of this patent, a plurality of negative resistance avalanche devices, such as the impact avalanche and transit time (IMPATT) diode, are mounted on one end of a coaxial cable, the other end of which is terminated by a matched impedance. The midportion of each cable is coupled to a common cavity resonator to provide a combined power output which is delivered by a wave guide connected to the resonator.
A similar microwave oscillator using the IMPATT type avalanche diodes is described in U.S. Pat. No. 3,984,788 to Peyrat entitled "Negative Resistance Microwave Power Generator". A plurality of IMPATT diodes are connected at one end to a coaxial transmission line, the other end of which terminates in an impedance close to the characteristic impedance of the coaxial line. These transmission lines are electromagnetically coupled to a common cavity resonator. At least one additional oscillator is electrically coupled to the resonator at a point where the electric field is at a maximum, thereby increasing the volumetric power delivered by 50%. The generated electromagnetic energy is transmitted to an external circuit, i.e. an antenna or the like through a wave guide.
For power levels above tens or hundreds of watts, the semiconductor devices enumerated above have not proven satisfactory. The size of devices needed for high power generation places a limit on their response time, making them unusable at microwave frequencies.